A method for preparing a heterojunction perovskite photodetector
By fabricating n-type three-dimensional perovskite thin films in an air atmosphere and transforming part of the interface into a p-type quasi-two-dimensional structure, a heterojunction was constructed, which solved the problems of high cost and carrier recombination loss of perovskite photodetectors and achieved high efficiency photoelectric performance and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2023-03-23
- Publication Date
- 2026-05-29
AI Technical Summary
Existing perovskite photodetectors require expensive organic materials during fabrication, resulting in high costs and significant interfacial recombination losses. Furthermore, traditional pin structures lack the ability to directionally drive charge carriers, which affects device performance.
A dense and smooth n-type three-dimensional perovskite thin film was prepared in an air atmosphere. The nucleation density was increased by spin coating and antisolvent immersion. Combined with large-group organic halides, the interface was transformed into a p-type quasi-two-dimensional structure to construct a heterojunction and reduce carrier recombination loss.
High-quality perovskite thin film deposition was achieved, which enhanced the directional transport of charge carriers, improved external quantum efficiency and detectivity, reduced fabrication costs, and ensured good device stability.
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Figure CN116634821B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to perovskite photodetectors, and particularly to a method for fabricating a heterojunction perovskite photodetector. Background Technology
[0002] Organic halide perovskites (such as MAPbI3) are widely used in high-performance photodetectors. Existing reports classify typical perovskite photodetector structures into mesoporous and planar structures, both of which are believed to operate using pin structures. However, pin-type photodetectors require expensive organic materials as the p-type and n-type transport layers, increasing the fabrication process and cost, and potentially leading to carrier recombination losses at the interface between the perovskite and different transport layers. Furthermore, traditional pin-type perovskite photodetectors rely on the transport layer to extract photogenerated carriers at the interface; the perovskite light-absorbing layer lacks directional driving capabilities, resulting in significant recombination losses during carrier transport. Therefore, fabricating perovskite pn-type structure photodetectors with the ability to promote directional carrier transport and minimize carrier recombination losses is of great significance. Moreover, known perovskite pn junctions are fabricated under strictly controlled inert environments using complex methods, resulting in high device fabrication costs and hindering the commercialization of perovskite photodetector devices. Summary of the Invention
[0003] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the present invention aims to provide a method for preparing a heterojunction perovskite photodetector. The prepared heterojunction perovskite photodetector has the advantages of high external quantum efficiency and high detectivity, and is simple to prepare.
[0004] The objective of this invention is achieved through the following technical solution:
[0005] A method for fabricating a heterojunction perovskite photodetector includes the following steps:
[0006] An electron transport layer is fabricated on a substrate with electrodes;
[0007] Lead iodide (PbI2) and lead chloride (PbCl2) were dissolved in a mixed solution of dimethylformamide, N-methylformamide and N-methylpyrrolidone to obtain a PbI2-PbCl2 precursor solution.
[0008] In an air atmosphere, the PbI2-PbCl2 precursor solution is spin-coated onto the electron transport layer. After uniform spreading, it is immediately immersed in the antisolvent of isopropanol (IPA). After crystallization, a PbI2-PbCl2 film is obtained.
[0009] Methylamine iodide solution (MAI) was spin-coated onto the PbI2-PbCl2 film, and then vacuum annealed to obtain an n-type three-dimensional perovskite film.
[0010] Phenethylammonium bromide was dissolved in isopropanol to obtain a long-chain ligand solution of a large-group organic halide;
[0011] The long-chain ligand solution is spin-coated onto the n-type three-dimensional perovskite film and vacuum annealed to obtain a perovskite heterojunction film; the perovskite heterojunction film includes a lower n-type three-dimensional perovskite layer and an upper p-type quasi-two-dimensional perovskite layer.
[0012] A hole transport layer, a hole blocking layer, and an anode are sequentially fabricated on the perovskite heterojunction thin film to obtain a heterojunction perovskite photodetector.
[0013] Preferably, the electron transport layer is one of tin oxide, zinc oxide, or nickel oxide.
[0014] Preferably, the hole transport layer is 2,2',7,7'-tetratetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (spiro-OMeTAD), poly(9-vinylcarbazole) (PVK), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'- One of the following: biphenyl-4,4'-diamine (TPD), 4,4',4'-tris(carbazole-9-yl)triphenylamine (TCTA), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-alt-(9,9-di-n-octylfluorenyl-2,7-diyl)] (TFB).
[0015] Preferably, the electron blocking layer is one of molybdenum trioxide (MoO3), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN).
[0016] Preferably, in the step of spin-coating the PbI2-PbCl2 precursor solution onto the electron transport layer, the spin-coating time is 4-5 seconds.
[0017] Preferably, in the step of spin-coating the PbI2-PbCl2 precursor solution onto the electron transport layer, the spin-coating speed is 15-18 r / s. 2 The acceleration will increase the rotational speed to 4000-4200 rpm.
[0018] Preferably, the step of spin-coating the methylamine iodide solution onto the PbI2-PbCl2 film and then vacuum annealing to obtain an n-type three-dimensional perovskite film specifically involves:
[0019] A methyl iodide solution was spin-coated onto the PbI2-PbCl2 film at a speed of 4000-4200 rpm, and then vacuum annealed at 130-140°C for 1-2 minutes to obtain an n-type three-dimensional perovskite film.
[0020] Preferably, the molar ratio of lead iodide to lead chloride is 4.5:1 to 5:1.
[0021] Preferably, the anode is one of aluminum (Al), silver (Ag), or gold (Au); more preferably, the anode is aluminum, which can significantly improve the normalized detection rate.
[0022] Preferably, the concentration of phenylethylammonium bromide in the long-chain ligand solution is 0.002–0.003 mol / L.
[0023] Preferably, the substrate is one of glass, quartz, polyethylene terephthalate (PET), polyimide (PI), or polydimethylsiloxane (PDMS).
[0024] Preferably, the concentration of the methyl iodide is 0.2 to 0.6 mol / L.
[0025] Preferably, the electron transport layer is prepared by: diluting the electron transport material with deionized water, spin-coating it onto an ITO electrode substrate treated with ultraviolet ozone, and annealing it to obtain the electron transport layer; wherein the annealing temperature is 160-200°C and the annealing time is 30-40 minutes.
[0026] Preferably, the hole blocking layer has a thickness of 4-5 nanometers, and the anode has a thickness of 80-120 nanometers.
[0027] The principle of this invention is as follows:
[0028] The method for preparing a heterojunction perovskite photodetector according to the present invention firstly prepares a dense and smooth n-type three-dimensional perovskite thin film in an air atmosphere, and then spin-coates a long-chain ligand onto the three-dimensional perovskite by introducing a long-chain ligand. A large-group organic halide is then used to transform part of the interface of the n-type three-dimensional perovskite into a p-type quasi-two-dimensional perovskite structure, thereby constructing a planar perovskite heterojunction. This invention, by utilizing a large-group organic halide to transform part of the interface of the n-type three-dimensional perovskite into a p-type quasi-two-dimensional perovskite structure, also avoids the problem of easily washing away the perovskite grains when preparing perovskite thin film stacks using the air spin-coating method.
[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0030] (1) The method for preparing a heterojunction perovskite photodetector of the present invention obtains a dense and smooth n-type three-dimensional perovskite thin film in an air atmosphere. A two-step method of short-time spin coating-antisolvent immersion-dynamic spin coating is used to prepare a high-quality perovskite thin film in air. In the first step, before nucleation, the spin-coated lead halide precursor of PbI2-PbCl2 is immersed in an antisolvent through short-time spin coating. The antisolvent rapidly precipitates crystal nuclei, thereby increasing the nucleation density and obtaining a uniform and smooth thin film. Secondly, a dynamic spin coating of an organic ammonium salt solution is used to reduce the influence of moisture on MA during the perovskite formation process. + The resulting solvation effect suppresses the Oswald ripening effect during the process, thereby overcoming the grain coarsening problem. Simultaneously, by utilizing large-group organic halides to transform part of the interface of the n-type three-dimensional perovskite into a p-type quasi-two-dimensional perovskite structure, the problem of washing away the perovskite grains during perovskite thin film stacking using air spin-coating is avoided. Therefore, the heterojunction perovskite photodetector prepared by this invention exhibits high film quality, excellent photoelectric performance and stability, and achieves a significant improvement in external quantum efficiency and detectivity.
[0031] (2) The method for preparing a heterojunction perovskite photodetector according to the present invention comprises a lower n-type three-dimensional perovskite layer and an upper p-type quasi-two-dimensional perovskite layer. The heterojunction structure forms an internal electric field, enhancing the directional transport of charge carriers and reducing carrier recombination. Furthermore, the long-chain ligands in the quasi-two-dimensional structure exhibit strong hydrophobicity, and their introduction improves the stability of the perovskite photodetector to a certain extent. The normalized detectivity of the final device is close to 1×10⁻⁶. 13 Jones, and can withstand higher bias voltages compared to single-junction perovskite photodetectors.
[0032] (3) The method for preparing heterojunction perovskite photodetectors of the present invention does not require preparation in an inert gas atmosphere, and the preparation is simple and low in cost.
[0033] (4) In the method for preparing a heterojunction perovskite photodetector of the present invention, aluminum is preferred as the anode, which can improve the normalized detection rate. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the structure of the heterojunction perovskite photodetector prepared in Example 1 of the present invention.
[0035] Figure 2 This is the current-voltage curve of the heterojunction perovskite thin film used in Example 1 of the present invention.
[0036] Figure 3 This is a graph showing the external quantum efficiency of the heterojunction perovskite photodetector in Example 1 of this invention.
[0037] Figure 4 This is a dark current curve of the heterojunction perovskite photodetector in Example 1 of the present invention.
[0038] Figure 5 This is a normalized detectivity curve of the heterojunction perovskite photodetector in Example 1 of the present invention.
[0039] Figure 6 This is a structural diagram of the pin-type perovskite photodetector in Comparative Example 1 of this invention.
[0040] Figure 7 This is a summary graph of the external quantum efficiency of the three perovskite photodetectors prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.
[0041] Figure 8 This is a summary graph of the normalized detectivity of the three perovskite photodetectors prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.
[0042] Figure 9 This is a summary X-ray diffraction diagram of the perovskite light absorption layer in the three perovskite photodetectors of Example 1, Comparative Example 1, and Comparative Example 2 of this invention.
[0043] Figure 10 This is a graph showing the external quantum efficiency of the perovskite photodetector in Embodiment 2 of the present invention.
[0044] Figure 11 This is a normalized detectivity curve of the perovskite photodetector in Embodiment 2 of the present invention. Detailed Implementation
[0045] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.
[0046] The terminology used in this invention generally has the meanings commonly understood by those skilled in the art, unless otherwise stated.
[0047] In the following embodiments, the ITO glass is processed using the following method:
[0048] Using 3 cm × 3 cm ITO glass slides, first ultrasonically clean them with a cleaning solution for 90 minutes, then rub and blow away the surface water droplets with nitrogen gas. Finally, bake them in a vacuum oven at 120℃ for 30 minutes until all moisture is removed.
[0049] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following embodiments are commercially available.
[0050] Example 1
[0051] This embodiment provides a heterojunction type perovskite photodetector, the structure of which is as follows: Figure 1 As shown, from bottom to top, it includes a substrate 1, a cathode 2, an electron transport layer 3, an n-type three-dimensional perovskite layer 4, a p-type quasi-two-dimensional perovskite layer 5, a hole transport layer 6, an electron blocking layer 7, and an anode 8. The fabrication method is as follows:
[0052] (1) Prepare perovskite precursor solutions according to the concentrations in Table 1.
[0053] (2) Prepare a 5% tin oxide solution, spin-coat it onto ITO glass at 4000 rpm for 10 seconds, and anneal it at 180°C for 30 minutes to obtain a SnO2 layer.
[0054] (3) The mixed precursor solution of lead iodide and lead chloride prepared in step (1) is spin-coated at 4000 rpm for 5 seconds onto the SnO2 layer prepared in step (2). The intermediate phase liquid is quickly immersed in isopropanol antisolvent. After crystallization, the methyl iodide solution is spin-coated at 4000 rpm for 5 seconds and annealed at 120°C for 2 minutes to obtain an n-type three-dimensional perovskite film.
[0055] (4) Prepare a 0.0025 mol / L phenylethyl ammonium bromide solution and spin-coat it at 4000 rpm for 5 seconds onto the n-type three-dimensional perovskite film prepared in step (3). Then, vacuum anneal it at 135 °C for 1 minute to obtain a heterojunction perovskite film. The perovskite heterojunction film includes a lower n-type three-dimensional perovskite layer and an upper p-type quasi-two-dimensional perovskite layer.
[0056] (5) Prepare a 0.06 mol / L spiro-OMeTAD solution and spin-coat it onto the perovskite film prepared in step (4) at a speed of 4000 rpm for 30 seconds to obtain a hole transport layer.
[0057] (6) In the vacuum evaporation chamber of the substrate after the above steps are completed, 5 nm MoO3 and 100 nm aluminum electrodes are deposited in sequence to obtain a heterojunction perovskite photodetector.
[0058] Table 1. Formulation of perovskite precursor solution (unit: mol / L)
[0059]
[0060] Figure 2The figure shows the current-voltage curve of the perovskite detector used as the perovskite light-absorbing layer in the embodiment. As can be seen from the figure, the current of the perovskite detector changes very little with voltage under negative bias, and changes significantly with voltage under positive bias, which shows a good rectification effect. This indicates that the p-type perovskite and n-type perovskite form a good heterojunction. Figure 3 The figure shows the external quantum efficiency curve of the heterojunction perovskite photodetector involved in the embodiment. As can be seen from the figure, the external quantum efficiency of the device increases significantly with the increase of reverse bias voltage. Figure 4 The dark current diagram of the heterojunction perovskite photodetector involved in Example 1 shows that the dark current increases with the increase of the reverse bias voltage. The detectivity of the device was calculated as follows: Figure 5 As shown, at a bias voltage of 0V, the detectivity at a wavelength of 740 nm reaches approximately 1×10⁻⁶. 13 Jones. It still exhibits good optoelectronic performance when the bias voltage is applied to -3V.
[0061] Comparative Example 1
[0062] This comparative example provides a pin-type perovskite photodetector (structure as follows). Figure 6 As shown in the figure, from bottom to top, it includes a substrate 9, a cathode 10, an electron transport layer 11, a perovskite layer 12, a hole transport layer 13, an electron blocking layer 14, and an anode 15. The fabrication method is as follows:
[0063] (1) Prepare perovskite precursor solutions according to the concentrations in Table 1.
[0064] (2) Prepare a 5% tin oxide solution, spin-coat it onto ITO glass at 4000 rpm for 10 seconds, and anneal it at 180°C for 30 minutes to obtain a SnO2 layer.
[0065] (3) The mixed precursor solution of lead iodide and lead chloride prepared in step (1) is spin-coated at 4000 rpm for 5 seconds onto the SnO2 layer prepared in step (2). The intermediate phase liquid is quickly immersed in isopropanol antisolvent. After crystallization, the methyl iodide solution is spin-coated at 4000 rpm for 5 seconds and annealed at 120°C for 2 minutes to obtain a perovskite film.
[0066] (4) Prepare a 0.06 mol / L spiro-OMeTAD solution and spin-coat it onto the perovskite film prepared in step (3) at a speed of 4000 rpm for 30 seconds to obtain a hole transport layer.
[0067] (5) In the vacuum evaporation chamber of the substrate after the above steps are completed, 5 nm MoO3 and 100 nm aluminum electrodes are deposited in sequence to obtain a pin-type perovskite photodetector.
[0068] Comparative Example 2:
[0069] This comparative example provides a heterojunction perovskite photodetector with a high concentration of long-chain ligands. Its structure is the same as the heterojunction perovskite photodetector prepared in Example 1, and the preparation method is as follows:
[0070] (1) Prepare perovskite precursor solutions according to the concentrations of each material in Table 1.
[0071] (2) Prepare a 5% tin oxide solution, spin-coat it onto ITO glass at 4000 rpm for 10 seconds, and anneal it at 180°C for 30 minutes to obtain a SnO2 layer.
[0072] (3) The mixed precursor solution of lead iodide and lead chloride prepared in step (1) is spin-coated at 4000 rpm for 5 seconds onto the SnO2 layer prepared in step (2). The intermediate phase liquid is quickly immersed in isopropanol antisolvent. After crystallization, the methyl iodide solution is spin-coated at 4000 rpm for 5 seconds and annealed at 120°C for 2 minutes to obtain an n-type perovskite film.
[0073] (4) Prepare a 0.005 mol / L phenylethyl ammonium bromide solution, spin-coat it onto the perovskite film prepared in step (3) at a speed of 4000 rpm for 5 seconds, and anneal it in vacuum at 135 °C for 1 minute to obtain a heterojunction perovskite film.
[0074] (5) Prepare a 0.06 mol / L spiro-OMeTAD solution and spin-coat it onto the perovskite film prepared in step (4) at a speed of 4000 rpm for 30 seconds to obtain a hole transport layer.
[0075] (6) In the vacuum evaporation chamber of the substrate after the above steps are completed, 5 nm MoO3 and 100 nm aluminum electrodes are deposited in sequence to obtain a heterojunction perovskite photodetector.
[0076] Figure 7 The graph compares the external quantum efficiency (EQE) of the three types of perovskite photodetectors prepared above. As can be seen from the graph, the heterojunction perovskite photodetector prepared with a low concentration of long-chain ligands exhibits the highest EQE. Compared to pin-type perovskite photodetectors, the presence of the heterojunction structure enables directional driving within the perovskite light-absorbing layer, reducing recombination losses during photogenerated carrier transport and effectively improving the device's EQE. For heterojunction perovskite photodetectors with a high concentration of long-chain ligands, the introduction of these ligands results in a thicker quasi-two-dimensional perovskite film, making carrier transport difficult and causing significant recombination losses; therefore, the EQE performance of this type of device is very low. Correspondingly, Figure 8The comparison of normalized detectivity of the three perovskite photodetectors shown also demonstrates the excellent performance of the heterojunction perovskite photodetector prepared by introducing low concentrations of long-chain ligands. Figure 9 The images show X-ray diffraction patterns of perovskite films with low concentrations of long-chain ligands, no long-chain ligands, and high concentrations of long-chain ligands. This indicates the existence of a certain quasi-two-dimensional structure in the perovskite films, further proving that the long-chain ligands were successfully introduced into the perovskite films.
[0077] Example 2
[0078] This embodiment uses silver (Ag) as the anode, and its structure is the same as in Example 1. The preparation method is as follows:
[0079] (1) Prepare perovskite precursor solutions according to the concentrations in Table 1.
[0080] (2) Prepare a 5% tin oxide solution, spin-coat it onto ITO glass at 4000 rpm for 10 seconds, and anneal it at 180°C for 30 minutes to obtain a SnO2 layer.
[0081] (3) The mixed precursor solution of lead iodide and lead chloride prepared in step (1) is spin-coated at 4000 rpm for 5 seconds onto the SnO2 layer prepared in step (2). The intermediate phase liquid is quickly immersed in isopropanol antisolvent. After crystallization, the methyl iodide solution is spin-coated at 4000 rpm for 5 seconds and annealed at 120°C for 2 minutes to obtain an n-type perovskite film.
[0082] (4) Prepare a 0.0025 mol / L phenylethyl ammonium bromide solution, spin-coat it onto the perovskite film prepared in step (3) at a speed of 4000 rpm for 5 seconds, and vacuum anneal it at 135 °C for 1 minute to obtain a heterojunction perovskite film.
[0083] (5) Prepare a 0.06 mol / L spiro-OMeTAD solution and spin-coat it onto the perovskite film prepared in step (4) at a speed of 4000 rpm for 30 seconds to obtain a hole transport layer.
[0084] (6) In the vacuum evaporation chamber of the substrate after the above steps are completed, 5 nm MoO3 and 100 nm silver electrodes are deposited sequentially to obtain a heterojunction perovskite photodetector.
[0085] Figure 10 The graph shows the external quantum efficiency of the heterojunction perovskite photodetector in this embodiment. As can be seen from the graph, the external quantum efficiency of the device increases significantly with the increase of the reverse bias voltage. Figure 11This is a normalized detectivity curve for the heterojunction perovskite photodetector of this embodiment. Compared to aluminum, silver as an electrode is not well modified by MoO3, resulting in higher noise in the device. Consequently, the calculated normalized detectivity is lower than that of Example 1, which uses aluminum as an electrode.
[0086] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for fabricating a heterojunction perovskite photodetector, characterized in that, Includes the following steps: An electron transport layer is fabricated on a substrate with electrodes; Lead iodide and lead chloride were dissolved in a mixed solution of dimethylformamide, N-methylformamide and N-methylpyrrolidone to obtain a PbI2-PbCl2 precursor solution. In an air atmosphere, the PbI2-PbCl2 precursor solution is spin-coated onto the electron transport layer. After uniform spreading, it is immediately immersed in the antisolvent of isopropanol. After crystallization, a PbI2-PbCl2 film is obtained. A methyl iodide solution was spin-coated onto the PbI2-PbCl2 film, and then vacuum annealed to obtain an n-type three-dimensional perovskite film. Phenethylammonium bromide was dissolved in isopropanol to obtain a long-chain ligand solution; The long-chain ligand solution is spin-coated onto the n-type three-dimensional perovskite film and vacuum annealed to obtain a perovskite heterojunction film; the perovskite heterojunction film includes a lower n-type three-dimensional perovskite layer and an upper p-type quasi-two-dimensional perovskite layer. A hole transport layer, an electron blocking layer, and an anode are sequentially fabricated on the perovskite heterojunction thin film to obtain a heterojunction perovskite photodetector.
2. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The electron transport layer is one of tin oxide, zinc oxide, or nickel oxide.
3. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The hole transport layer is one of 2,2',7,7'-tetratetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, poly(9-vinylcarbazole), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, 4,4',4'-tris(carbazole-9-yl)triphenylamine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-alt-(9,9-di-n-octylfluorene-2,7-diyl)].
4. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The electron blocking layer is one of molybdenum trioxide (MoO3), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone, and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene.
5. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, In the step of spin-coating the PbI2-PbCl2 precursor solution onto the electron transport layer, the spin-coating time is 4-5 seconds.
6. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, In the step of spin-coating the PbI2-PbCl2 precursor solution onto the electron transport layer... During spin coating, use 15~18 r / s 2 The acceleration will increase the rotational speed to 4000~4200rpm.
7. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The process of spin-coating a methyl iodide solution onto the PbI2-PbCl2 film and then vacuum annealing to obtain an n-type three-dimensional perovskite film is as follows: A methyl iodide solution was spin-coated onto the PbI2-PbCl2 film at a speed of 4000~4200 rpm, and then vacuum annealed at 130~140℃ for 1~2 minutes to obtain an n-type three-dimensional perovskite film.
8. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The molar ratio of lead iodide to lead chloride is 4.5:1 to 5:
1.
9. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, The anode is one of aluminum, silver, or gold.
10. The method for preparing a heterojunction perovskite photodetector according to claim 1, characterized in that, In the long-chain ligand solution, the concentration of phenylethylammonium bromide is 0.002~0.003 mol / L.